1. Field of the Invention.
The present invention relates to batch fabricated differential pressure cells having diaphragms formed of brittle materials which are provided with overpressure protection, and mounted in a housing to insure proper operation at a subtantial range of static line pressure.
2. Description of the Prior Art.
U.S. Pat. No. 4,572,000 shows a pressure sensor having a brittle diaphragm which when at an overpressure is flat against a flat support plate. In this patent, the diaphragm is bulged outwardly from its support plate under an initial pressure and made so that it will rest against the support plate and be substantially flat when under maximum pressure.
Additional prior devices utilizing brittle diaphragms that have edge support rims also are known, wherein the sensing may be done by capacitance sensing or using strain gages mounted on the diaphragm itself.